Lubricating oil composition



Patented Nov. 21, 1939 UNITED STATES PATENT OFF-ICE LUBRICATING on. COMPOSITION Arnold c. Vobach, Whiting, ma, assignor to Sinclair No Drawing.

Refining Company, New York, N. Y., a corporation of Maine Application July 27, 1937, Serial No. 155,921

2 Claims. (01. 87-9) stearates, and an aromatic stearic acid, stearic acid or palmitic acid. Thearomatic stearic acids useful for the purposes of my invention include phenyl stearic acid, tolyl stearic acid, xylylystearic acid, naphthyl stearic acid and anthracyl stearic acid. The addition of such zinc soaps, or other metallic soaps, and free acids should be made in amount or amounts insufficient materially to alter the normally liquid character of the petroleum lubricating oil itself, for example, from 0.5%-2.5% on the oil.

The trend of development in internal combustion engines has imposed increasing burdens upon the oils used for their lubrication, particularly with respect to operating temperatures and pressures. At present, the Diesel type of engine probably represents extreme requirements in both of these respects, but it is not alone in the imposition of severe burdens upon the lubricating oil used. The useful operating life of a lubricating oil, in such service, is determined, in large measure, by its thermal stability and by its physical capacity to continue functioning as a lubricant,

at the high temperatures and high pressures encountered. One measure of thermal stability is resistance to oxidation, and the consequent tendency to form sludge, but in another aspect the 0 effect of thermal instability is determined not only by the extent of oxidation or decomposition but also by the character of the products of such decomposition or oxidation and by the extent and location, within the. engine, of deposits of such products.

' The improved lubricating oil compositions of my invention have, in addition to the lubricating properties of the petroleum ofls of which they are compounded, a high solvent capacity forsludge, of the character formed by oxidation of petroleum lubricating oils and, perhaps of even greater importance, the properties of rendering deposits of sludge and carbon" within the engine soft and friable rather than hard and coherent and-of disintegrating and removing such deposits as an incident of the normal operation ofthe engine; In this aspect, the lubricating oil compositions of my invention render the engines in which they are used self-cleaning to an important extent.

In the'Diesel type of engine, for example, the

:high temperatures to which the lubricating oil is subjected, particularly at the top of the stroke, frequently cause deposition of sludge and carbonization in the groove for andbehind one or more 10 of the piston rings. Using parafl'lnic type lubricating oils such difliculties are usually more pronounced with respect to the uppermost ring; using naphthenic type lubricating'oil they are usually more pronounced with respect to the lower 15 rings. Consequent sticking of the rings rapidly deprives the piston and cylinder wall of proper lubrication inducing excess wear and, frequently, scoring of the cylinder wall. The formation of such carbon deposits, hard enough 20 and coherent enough to involve sticking of the rings, is materially retarded, if not avoided, by the use of the improved lubricating oil compositions of my invention, and in this aspect the self-cleaning properties of the lubricating oil com- 25 positions of my invention, with respect to the engine, make a mere change of oil a substitute, economical with respect to both loss of service time and cost, for many otherwise necessary cleaning and repair jobs.

Zinc phenyl stearate, or mixtures including zinc phenyl stearate and zinc stearate, for compounding the improved lubricating oils of my invention, can be produced as follows:

1 part (parts by weight) of pulverulent anhy- 35 drous aluminum; chloride is stirred into 4 parts of commercial benzol boiling below C.,

this stirring being efl'ected at atmospheric pres- -made over a period of about an hour. This reaction is carried out at atmospheric pressure 45 and is started at ordinary temperature. The temperature rise incident tothe reaction is limited so that the maximum temperature approximates 180 F., the temperature being controlled either by cooling or by regulating the rate of 50 addition of the oleic acid. The reaction mixture is maintained at a temperature of -180 F. for 6 or 7 hours. For at least the last half hour of this period'the reaction mixture is held at F. to insure completion of the reaction and 5s to assist-in stripping hydrochloric acid from the reaction mixture. The reaction product, a pasty liquid, is then added to about to V2 of its .volume of aqueous hydrochloric acid, 15% to 20% HCl, at ordinary temperature. The ensuing reaction brings the temperature, for example, to about 170 F. This reaction mixture is thoroughly stirred and the aqueous acid solution is then separated from the oily product of the reaction, by decantation for example. This separated oily product is thoroughly washed with water, advantageously with hot water, in two successive stages with about of its volume of hot water in each stage'ior example. This washing should in any event be continued until a qualitative test for aluminum in the wash water is negative. After this washing, the reaction product is a thin, oily, dark green liquid. It is I allowed to stand to settle out any remaining material undergoing distillation is not heated other sources as follows: 1 part of phenyl stearic to any temperature much exceeding 640-650 F. for any period long enough to involve decomposition. When effecting the distillation under a vacuum of 4 millimeters of mercury absolute pressure, a first cut of about 25% is taken ofl up to the point at which the temperature 01. the liquid in the still reaches 466 F. and a second cut qf. about 53% is taken oil! as the temperature of the liquid in-the still rises from 466 F. to 590- F. The' zinc phenyl stearate may then be prepared from the phenyl stearic acid product contained in the above-described first and second fractions,- or from phenyl stearic acid, or phenyl stearic acid mixtures obtained from acid is completely saponifled at room temperature with the theoretical quantity of 30 B. sodium hydroxide solution. When saponification is complete 10 parts of water are added and the mixturestirred until the sodium phenyl stearate is-completely dissolved. To this solution is then added an aqueous solution of zinc chloride, this solution being suflicient concentration and bein g1' added'in sufllcient excess not only to preptate but also to coagulate the zinc phenyl stearate. The: aqueous solution is decanted from the insoluble zinc phenyl stearate which is then washed thoroughly with water and thereafter dried. The zinc soaps of other aromatic stearic acids may be similarly prepared.

The major portion of the product resulting from the saponiflcation and precipitation oi the 5 second distillate traction derived as described above is zinc phenyl stearate as that term is used herein, although I intend to refer to this same material by whatever process it may be made. Also, the major portion of the product which results if the first distillate fraction as well as the second is saponifled and precipitated as described is a mixture 01 zinc phenyl stearate and zinc stearate.

In compounding the improved liquid lubricating oil compositions of my invention with the usual petroleum lubricating coils,-the zinc phenyl stearate, or'the mixture of zinc phenyl stearate and zinc stearate, produced as described above,

are added to the lubricating oil in proportions ranging from about 0.5% up to about 2.0% or 2.5% by weight on the oil. A composition consisting chiefly of a South Texas pale oil having a viscosity of 500 seconds at 100 F., Saybolt .Universal andboiling aproxlmately 10% up to 700 F. and 90% up to 900 F. and 1.33% by weight on the oil of a mixture of zinc phenyl stearate and zinc stearate is particularly advantageous. The Indiana Oxidation Test, described in the S. A. E. Journal 34, 172-173 (1934), on one 3 such composition containing zinc phenyl stearate was 18.5 hours, the corresponding value for the lubricating oil alone being 13.5 hours. This same lubricating oil composition, when exposed to highly heated surfaces, decomposed to produce a residue consisting of a soft friable coke in contrast to the hard and adherent residue resulting when the lubricating oil alone was so exposed.

Any tendency of the zinc phenyl stearate abnormally toincrease the viscosity of the oil to which it is added may be reduced by the addition of a small amount of free phenyl stearic acid, free stearic acid or free palmitic acid. In

a. lubricating oil composition such as that speciflcally described above, for example, the addition of 7 7l,-8% of the acid, based on the soap, is

effective for this purpose, although proportions up to about 20% are sometimes advantageous.

I claim:

LA liquid lubricating oil composition comprising a petroleum lubricating oil and zinc phenyl stearate.

2. A liquid lubricating oil composition comprising a petroleum lubricating oil and a. zinc aromatic stearate.

ARNOLD C. VOBACH. 

